The objective of my research is to place the evolution of potato genomes in phylogenetic context, with respect to four clades of potato and the non-tuber-bearing outgroup relatives in Solanum sect. Etuberosum, as define by chloroplast DNA restriction site data. It focuses on one of these four clades, the Solanum Piurana clade. I am also examining potato late blight linkages. All of this work is done in collaboration with colleagues at the International Potato Center in Peru (Meredith Bonierbale co-PI). To accomplish these objectives I am building a genetic map of an intra-series Piurana clade cross by single-copy genomic probes from tomato, kindly supplied by Stephen Tanksley at Cornell University. The intention is to determine whether this clade is distinguished by chromosome rearrangements. As well, the species has been chosen to be late blight resistant and susceptible, so that a late blight genetic linkage map can be constructed.